Electric thermal storage steam device

Abstract

The present invention discloses an electric heat storage steam device, comprising: a housing, a circulating fan, an electric heat storage body, a steam generating device and a heat exchanger. The housing defines a heat storage chamber, a high-temperature air duct connected to an air outlet and a low-temperature air duct connected to an air inlet. The circulating fan is used to drive the airflow in the low-temperature air duct to flow to the heat storage chamber, and drive the airflow in the heat storage chamber to flow to the high-temperature air duct. The electric heat storage body arranged in the heat storage chamber generates heat after being energized and exchanges heat with the airflow to form hot air. The steam generating device comprises a heat-conducting air duct connected between the high-temperature air duct and the low-temperature air duct, a steam generator and a heat exchange tube bundle, and the heat exchange tube bundle is arranged in the steam generator for temperature compensation. The heat exchanger comprises a heat exchange air duct arranged between the high-temperature air duct and the low-temperature air duct, and the heat exchanger heats the water flowing through and inputs it into the steam generator to generate steam. According to the electric heat storage steam device of the embodiment of the present invention, the steam generator can still maintain a sufficient amount of steam generation when the heat storage of the electric heat storage body is less.

Description

Technical Field

[0001] The invention belongs to the technical field of clean energy heating, and in particular is an electric heat storage steam device. Background Art

[0002] In order to adjust the electricity consumption structure and encourage users to use electricity during off-peak hours, a strategy of different electricity prices in different time periods is adopted when supplying electricity. Specifically, the electricity price for residential or commercial electricity is high during the peak hours of daytime electricity consumption, and low during the off-peak hours of nighttime electricity consumption. If part of the electricity consumption is adjusted to the off-peak electricity consumption period, the difference between the peak and valley values ​​of power supply can be greatly narrowed, alleviating the tension of daytime power supply. There are now a variety of thermal storage devices that can convert electrical energy into thermal energy and store it.

[0003] In the existing electric heat storage technology, when the electricity stored in the electric heat storage device is converted into heat and supplied to the user end, the amount of heat stored in the electric heat storage body is relatively high. When the heat is transferred outward, it is usually through air heat transfer, water heat transfer or heat pipe heat transfer. When heat is transferred through air, the heat loss is large, so that the terminal heat obtained by the user end is insufficient or unstable; when heat is transferred through water, the heat transfer temperature is greatly limited, and the terminal heat form that can be used by the user end is limited; when heat is transferred through a heat pipe, the heat pipe is directly connected to the electric heat storage body, and its own heat resistance and corrosion resistance requirements are relatively high, and the product cost is high.

[0004] In addition, the layout of the electric heating wire group of the electric heat storage body in the existing heat storage chamber is unreasonable, resulting in low utilization of the electric heating wire or large heat loss, and uneven heating of the electric heat storage body. The heat stored in the electric heat storage body will decrease with the gradual use and release process, which will result in insufficient terminal heat obtained by the user end after the electric heat storage body is used for a long time during the day. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes an electric thermal storage steam device, which can ensure sufficient terminal steam consumption and solve the technical problem that the electric thermal storage body cannot meet the heat demand of the user end when the electric thermal storage body releases energy for a long time after a heat storage.

[0006] According to an embodiment of the present invention, an electric heat storage steam device comprises: a shell, wherein a heat storage chamber, a high-temperature air duct and a low-temperature air duct are defined in the shell, wherein the heat storage chamber has an air outlet and an air inlet, wherein the air outlet is connected to the high-temperature air duct, and the air inlet is connected to the low-temperature air duct; a circulating fan, wherein the circulating fan is used to drive the airflow in the low-temperature air duct to flow to the heat storage chamber, and drive the airflow in the heat storage chamber to flow to the high-temperature air duct; an electric heat storage body, wherein the electric heat storage body is arranged in the heat storage chamber, and when the electric heat storage body is energized, it generates heat and exchanges heat with the airflow passing through to form a heat storage chamber leading to the high-temperature air duct. Hot air; a steam generating device, the steam generating device comprising a heat-conducting air duct, a steam generator and a heat-exchange tube bundle, the heat-conducting air duct is connected between the high-temperature air duct and the low-temperature air duct to form a first circulation air duct with the shell, and at least a portion of the heat-exchange tube bundle is arranged in the steam generator to replenish the temperature of water in the steam generator; a heat exchanger, the heat exchanger comprising a heat-exchange air duct, the heat-exchange air duct is arranged between the high-temperature air duct and the low-temperature air duct to form a second circulation air duct with the shell, and the heat exchanger heats the water flowing through and inputs it into the steam generator to generate steam.

[0007] According to the electric heat storage steam device of the embodiment of the present invention, the electric heat storage body is arranged in the heat storage chamber, which can efficiently convert electrical energy into thermal energy and store it to form a high-temperature heat source, and heat the wind flowing through the electric heat storage body into high-temperature wind and transport it toward the air outlet and the high-temperature air duct. The high-temperature air duct, the heat-conducting air duct, and the low-temperature air duct are connected in sequence to form a first circulation air duct, and the high-temperature air duct, the heat-exchange air duct, and the low-temperature air duct are connected in sequence to form a second circulation air duct. When the electric heat storage body has sufficient heat storage, under the action of the circulating fan, the hot air coming out of the high-temperature air duct passes through the second circulation air duct and exchanges heat with the water in the heat exchanger, so that the water is quickly heated and transported to the steam generator to generate steam, and the steam can be transported to the user end. When the heat storage of the electric heat storage body is insufficient, the water that has only exchanged heat through the second circulation air duct has insufficient water temperature when entering the steam generator and the amount of steam generated is insufficient. The first circulation air duct is opened, and the hot air entering the first circulation air duct from the high-temperature air duct directly flows through the heat exchange tube bundle. The heat exchange tube bundle exchanges heat with the steam generator to form temperature compensation, ensuring that the steam generator can still maintain sufficient steam generation when the heat storage of the electric heat storage body is low.

[0008] According to an electric heat storage steam device according to an embodiment of the present invention, the steam generator has a water inlet and a high-temperature steam outlet, the heat exchange tube bundle includes a plurality of heat exchange tubes, the heat exchange tube bundle penetrates into the steam generator, two ends of the heat exchange tube bundle extend from the steam generator respectively to form a high-temperature end and a low-temperature end, the heat conduction air duct includes a high-temperature section and a low-temperature section, the high-temperature end is connected to the high-temperature section, the low-temperature end is connected to the low-temperature section, and the low-temperature section is connected to the low-temperature air duct.

[0009] According to the electric thermal storage steam device of one embodiment of the present invention, a switch valve is provided on the first circulation air duct to open and close the first circulation air duct, and an induced draft fan is also provided on the first circulation air duct.

[0010] According to a further embodiment of the present invention, a pressure transmitter is provided in the steam generator, and the pressure transmitter monitors the steam pressure in the steam generator and controls the opening and closing of the switch valve and the induced draft fan.

[0011] According to one embodiment of the present invention, the electric heat storage steam device further includes: an insulated water tank having a water outlet, a heat exchange water flow channel formed in the heat exchanger, and the water outlet being connected to the heat exchange water flow channel; and a water pump, the water pump being used to drive the water in the insulated water tank to be supplied toward the heat exchanger.

[0012] According to a further embodiment of the present invention, a condensate return pipe is connected between the steam generator and the insulated water tank, and a steam trap is provided on the condensate return pipe; and a water softener is connected to the water inlet end of the insulated water tank.

[0013] According to an electric heat storage steam device according to one embodiment of the present invention, an insulating heat preservation layer plate is provided around the electric heat storage body, a heat preservation cavity is formed between the insulating heat preservation layer plate and the shell, the heat storage cavity is formed inside the insulating heat preservation layer plate, and multiple layers of heat preservation bricks are provided in the heat preservation cavity, and the heat preservation bricks support the electric heat storage body.

[0014] According to an electric thermal storage steam device according to one embodiment of the present invention, the electric thermal storage body includes a heating element and multi-layer thermal storage bricks, the heating element is connected to a high-voltage power transmission device and electrically heats the thermal storage bricks to 800-850°C, the electric thermal storage body exchanges heat with the wind in the thermal storage chamber to form hot wind at 400-600°C and transports it to the high-temperature air duct.

[0015] Optionally, a first groove is formed on one side of the heat storage brick, and the first grooves of two adjacent heat storage bricks are connected to accommodate the heating element; a second groove is formed on one side of the heat storage brick, and two adjacent second grooves are connected to accommodate the temperature sensor.

[0016] Advantageously, the density of the heating element near the air outlet of the heat storage chamber is smaller than that of the heating element near the air inlet of the heat storage chamber.

[0017] Additional aspects and advantages of the invention will become apparent from the following description, or may be learned by practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0019] Figure 1 The figure is a schematic diagram of the overall structure of an electric thermal storage steam device in one embodiment of the present invention.

[0020] Figure 2 It is a schematic diagram of the partial structure of a steam generating device in one embodiment of the present invention.

[0021] Figure 3 It is a longitudinal cross-sectional view of an electric heat storage body in one embodiment of the present invention.

[0022] Figure 4 It is a side view of the local structure of an electric heat storage body in one embodiment of the present invention.

[0023] Reference numerals:

[0024] Electric thermal storage steam device 100;

[0025] Shell 1;

[0026] Heat storage chamber 11; high temperature air duct 12; low temperature air duct 13;

[0027] Circulation fan 2;

[0028] Electric heat storage body 31; heat storage brick 311; first groove 311A; second groove 311B; insulation layer 32; insulation brick 33; heating element 34; temperature sensor 35;

[0029] Steam generating device 4;

[0030] Heat conduction air duct 41; high heat section 411; low heat section 412; induced draft fan 413; mixing fan 414;

[0031] Steam generator 42; water inlet 421; high temperature steam outlet 422; pressure transmitter 423;

[0032] Heat exchange tube bundle 43; heat exchange tube 431; high temperature end 432; low temperature end 433; air distribution tube 434;

[0033] Heat exchanger 6; heat exchange air duct 61; heat exchange water flow channel 62;

[0034] Insulated water tank 7; water outlet 71; condensed water return port 72; steam trap 73; drain port 74; water inlet 75; condensed water return pipe 76;

[0035] Water pump 8;

[0036] Water softener 9; softened water equipment 91; water inlet valve 911; water outlet valve 912; automatic molten salt device 92;

[0037] High voltage power transmission equipment 10. DETAILED DESCRIPTION

[0038] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0039] In the description of the present invention, it is necessary to understand that the terms "longitudinal", "length", "up", "down", "front", "rear", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0040] The electric thermal storage steam device 100 according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0041] An electric heat storage steam device 100 according to an embodiment of the present invention includes: a housing 1 , a circulation fan 2 , an electric heat storage body 31 , a steam generating device 4 and a heat exchanger 6 .

[0042] Among them, Figure 1 As shown, a heat storage chamber 11, a high-temperature air duct 12 and a low-temperature air duct 13 are defined in the shell 1. The heat storage chamber 11 has an air outlet and an air inlet, the air outlet is connected to the high-temperature air duct 12, and the air inlet is connected to the low-temperature air duct 13. A relatively closed environment is formed inside the shell 1, so that the wind in the low-temperature air duct 13 enters the heat storage chamber 11, undergoes heat exchange, and then flows out from the high-temperature air duct 12.

[0043] The circulating fan 2 is used to drive the airflow in the low-temperature air duct 13 to flow to the heat storage chamber 11, and drive the airflow in the heat storage chamber 11 to flow to the high-temperature air duct 12. The circulating fan 2 allows air of different temperatures to be continuously circulated and blown between the high-temperature air duct 12, the low-temperature air duct 13, and the heat storage chamber 11.

[0044] The electric heat storage body 31 is arranged in the heat storage chamber 11. When the electric heat storage body 31 is powered on, it generates heat and exchanges heat with the airflow flowing through it to form hot air leading to the high-temperature air duct 12. The electric heat storage body 31 converts electrical energy into thermal energy and stores a certain amount of heat, so that a higher temperature is formed in the heat storage chamber 11. When the electric heat storage body 31 releases energy as a heat source, it gradually dissipates heat to the heat storage chamber 11 and exchanges heat with the air flowing through the heat storage chamber 11, forming heat exchange between solid and gas, and between gas and gas.

[0045] like Figure 1 and Figure 2As shown, the steam generating device 4 includes a heat-conducting air duct 41, a steam generator 42 and a heat exchange tube bundle 43, wherein the heat-conducting air duct 41 is connected between the high-temperature air duct 12 and the low-temperature air duct 13 to form a first circulation air duct with the shell 1. That is to say, when the circulating fan 2 is started, the wind can be selectively circulated through the first circulation air duct composed of the low-temperature air duct 13, the heat storage chamber 11, the high-temperature air duct 12 and the heat-conducting air duct 41, and the heat in the heat storage chamber 11 is continuously transported to the steam generator 42. At least part of the heat exchange tube bundle 43 is arranged in the steam generator 42 to supplement the temperature of the water in the steam generator 42. In this way, the heat transmitted to the heat exchange tube bundle 43 through the first circulation air duct is transmitted to the steam generator 42 to increase the temperature of the water inside the steam generator 42.

[0046] like Figure 1 As shown, the heat exchanger 6 includes a heat exchange air duct 61, which is arranged between the high temperature air duct 12 and the low temperature air duct 13 to form a second circulation air duct with the housing 1. The heat exchanger 6 heats the water flowing through and inputs it into the steam generator 42 to generate steam. That is to say, when the circulating fan 2 is started, the wind can be selectively circulated through the second circulation air duct composed of the low temperature air duct 13, the heat storage chamber 11, the high temperature air duct 12, and the heat exchange air duct 61, and the heat in the heat storage chamber 11 is continuously transported to the heat exchanger 6, and the water in the heat exchanger 6 is heated to a point close to the boiling point and directly transported to the steam generator 42 to generate steam.

[0047] As can be seen from the above structure, in the electric thermal storage steam device 100 of the embodiment of the present invention, the electric thermal storage body 31 is arranged in the thermal storage chamber 11, which can efficiently convert electrical energy into thermal energy storage to form a high-temperature heat source, especially when the electric thermal storage body 31 uses electricity at night and converts electrical energy into thermal energy storage, it will greatly reduce the cost of electricity use and reduce the difference between the nighttime electricity consumption valley value and the daytime electricity consumption peak value.

[0048] The high-temperature air duct 12, the heat-conducting air duct 41, and the low-temperature air duct 13 are sequentially connected to form a first circulation air duct, and the high-temperature air duct 12, the heat-exchange air duct 61, and the low-temperature air duct 13 are sequentially connected to form a second circulation air duct. When the electric heat storage body 31 has sufficient heat storage, under the action of the circulating fan 2, the hot air coming out of the high-temperature air duct 12 mainly passes through the second circulation air duct and exchanges heat with the water in the heat exchanger 6, so that the water is quickly heated and transported to the steam generator 42 to generate steam. The generated steam can be transported to the user end for use. For example, the user can use the high-temperature steam for domestic or industrial heat. The use of heat is not limited to heating, but can also be used for cooking, drying, dehydration and disinfection, etc., so that the terminal heat use forms are diversified.

[0049] When the heat storage of the electric heat storage body 31 is insufficient, the water that only exchanges heat through the second circulation air duct has insufficient water temperature when entering the steam generator, and the amount of steam generated is insufficient. At this time, the first circulation air duct is opened, and the hot air entering the first circulation air duct from the high-temperature air duct 12 directly flows through the heat exchange tube bundle 43. The heat exchange tube bundle 43 exchanges heat with the steam generator 42 to form temperature compensation, ensuring that the steam generator 42 can still maintain sufficient steam generation when the heat storage of the electric heat storage body 31 is less.

[0050] During the whole process, heat is transferred in a relatively closed space, with rapid heat transfer and high heat exchange efficiency. During heat transfer, the liquid is finally converted into high-temperature steam for output through gas-solid heat transfer, gas-gas heat transfer, and solid-liquid heat transfer. The heat transfer is efficient and the service life of the heat exchange tube bundle 43 is long. Compared with the prior art in which the heat exchange tube bundle 43 is directly contacted with the lava in the electric heat storage device and directly heat exchange is performed, the heat exchange tube bundle 43 of the present invention is in contact with the hot air in the heat-conducting air duct 41, and the hot air smoothly exchanges heat with the tube wall of the heat exchange tube bundle 43, which puts little pressure on the heat exchange tube bundle 43. The arrangement of the heat exchange tube bundle 43 is diversified (including the diversified connection relationship between the heat exchange tube bundle 43 and the heat-conducting air duct 41 and the steam generator 42, and also including the diversified structural form of the heat exchange tube bundle 43 itself), which effectively improves the heat exchange efficiency between the heat exchange tube bundle 43 and the hot air, and reduces the damage of the heat exchange tube bundle 43. The heat exchange tube bundle 43 does not need to withstand the extremely high heat of the lava, and the material of the heat exchange tube bundle 43 can be selected from a material with lower tolerance, thereby saving the equipment investment cost of the electric heat storage steam device 100.

[0051] In the description of the present invention, features defined as “first” or “second” may explicitly or implicitly include one or more such features, and are used to distinguish and describe the features, without any distinction in order or importance.

[0052] In some embodiments of the present invention, Figure 1 and Figure 2 As shown, the steam generator 42 has a water inlet 421 and a high-temperature steam outlet 422. The heat exchange tube bundle 43 includes a plurality of heat exchange tubes 431. The heat exchange tube bundle 43 penetrates into the steam generator 42. The two ends of the heat exchange tube bundle 43 extend from the steam generator 42 and form a high-temperature end 432 and a low-temperature end 433. The heat-conducting air duct 41 includes a high-temperature section 411 and a low-temperature section 412. The high-temperature end 432 is connected to the high-temperature section 411, and the low-temperature end 433 is connected to the low-temperature section 412. The low-temperature section 412 is connected to the low-temperature air duct 13. In other words, the heat exchange tube bundle 43 directly penetrates into the steam generator 42, and the tube wall of the heat exchange tube bundle 43 can directly exchange heat with the water in the steam generator 42. After the hot air is introduced into the heat exchange tube bundle 43, the heat is transferred to the water through the tube wall, so that the water in the steam generator 42 is directly heated and heated. Specifically, the water inlet 421 of the steam generator 42 is communicated with the hot water flow channel 62 for heat exchange, so as to allow the high boiling water that has been heat exchanged by the heat exchanger 6 to flow in.

[0053] Optionally, a plurality of heat exchange tubes 431 are arranged in parallel in the steam generator 42, which is conducive to the smooth flow of hot air.

[0054] Optional, such as Figure 1 and Figure 2 As shown, the high temperature end 432 and the low temperature end 433 are respectively integrated on the air distribution tube 434. The air distribution tube 434 connected to the high temperature end 432 mixes the air from the high temperature section 411 and distributes it in the heat exchange tube bundle 43; the air distribution tube 434 connected to the low temperature end 433 mixes and buffers the air exchanged through the heat exchange tube bundle 43, and guides it to the subsequent low temperature air duct 13.

[0055] Optionally, the middle tube wall of the heat exchange tube bundle 43 is integrally formed with the steam generator 42, and the two ends of the heat exchange tube bundle 43 form air duct interfaces. In this way, the tube wall of the heat exchange tube bundle 43 forms a partial tube wall of the steam generator 42, and the two ends of the heat exchange tube bundle 43 are connected to the heat conduction air duct 41 and the low-temperature air duct 13, with hot air entering at one end and cold air being discharged at the other end.

[0056] Optionally, a mounting hole is opened on the tube wall of the steam generator 42, and the heat exchange tube bundle 43 passes through the mounting hole and then passes out. A sealing component is installed at the mounting hole to seal it, so that the heat in the heat exchange tube bundle 43 is directly transferred to the water in the steam generator 42.

[0057] Advantageously, the high temperature end 432 of the heat exchange tube bundle 43 uses a manganese alloy tube, the low temperature end 433 uses a stainless steel fin tube, and the portion of the heat exchange tube bundle 43 extending into the steam generator 42 also uses a manganese alloy tube. The use of manganese alloy tubes is conducive to rapid heat transfer and heat exchange, and the use of stainless steel fin tubes is conducive to heat dissipation. The combination of manganese alloy tubes and stainless steel fin tubes is conducive to better function of the heat exchange tube bundle 43 and cost control.

[0058] Of course, the connection form of the heat exchange tube bundle 43, the heat conduction air duct 41 and the steam generator 42 of the present invention is not limited to the above structure, and can also be other structural forms.

[0059] For example, in some examples, the high temperature end 432 of the heat exchange tube bundle 43 is connected to the upwind direction of the heat conduction air duct 41, and the low temperature end 433 of the heat exchange tube bundle 43 is inserted into the steam generator 42, so that the heat absorbed by the heat exchange tube bundle 43 is transferred to the steam generator 42. In this example, the heat exchange tube bundle 43 can be formed as a U-shaped tube or a serpentine tube, and the U-shaped tube and the serpentine tube are partially located in the steam generator 42, and directly exchange heat with the water in the steam generator 42, so that the hot air can fully exchange heat with the water in the steam generator 42 when passing through the heat exchange tube bundle 43.

[0060] In some other examples, the heat exchange tube bundle 43 is coiled on the tube wall of the steam generator 42, and hot air flowing in from the heat conduction air duct 41 enters and passes out of the heat exchange tube bundle 43. The outer wall of the heat exchange tube bundle 43 transfers heat with the outer wall of the steam generator 42, and transfers heat to the water in the steam generator 42 to form compensation temperature.

[0061] Advantageously, in some embodiments, a first liquid level gauge (not shown) is also provided in the steam generator 42. The first liquid level gauge is connected to the control system and is used to detect the height of the water level in the steam generator 42. When the water level is lower than a preset value, the control system adds water to the steam generator 42.

[0062] In some embodiments of the present invention, a switch valve is provided on the first circulation air duct to open and close the first circulation air duct, and an induced draft fan 413 is also provided on the first circulation air duct. The first circulation air duct is opened or closed under the control of the switch valve, so that part of the hot air flowing out of the high-temperature air duct 12 flows toward the first circulation air duct, and the heat exchange tube bundle 43 can directly compensate for the temperature rise of the water in the steam generator 42. The induced draft fan 413 makes the wind in the first circulation air duct circulate quickly to increase the flux of the hot air in the heat exchange tube bundle 43 and improve the heat exchange efficiency between the heat exchange tube bundle 43 and the water. The opening of the first circulation air duct allows the water in the steam generator 42 to perform temperature compensation, which is particularly suitable for when the electric heat storage body 31 itself does not store enough heat, or when the steam demand at the user end surges, the amount of steam generated by the water in the steam generator 42 can meet the demand in time, ensuring the working efficiency of the electric heat storage steam device 100 and stably providing the required high-temperature steam to the user end.

[0063] Optionally, a pressure transmitter 423 is provided in the steam generator 42, and the pressure transmitter 423 monitors the steam pressure in the steam generator 42 and controls the opening and closing of the switch valve and the induced draft fan 413. When the pressure transmitter 423 detects that the steam pressure in the steam generator 42 does not meet the set value, the pressure transmitter 423 transmits a signal to the controller, and the controller controls the switch valve and the induced draft fan 413 to open; and when the pressure transmitter 423 detects that the steam pressure in the steam generator 42 is not less than the set value, the switch valve and the induced draft fan 413 remain closed.

[0064] Optionally, the first circulation air duct is further provided with a fan mixer 414, which is located downwind of the induced draft fan 413. After the fan mixer 414 is provided, the wind flowing from the first circulation air duct to the low-temperature air duct 13 can be more uniform, and the return air and circulation can be better.

[0065] In some embodiments of the present invention, Figure 1 As shown, the electric thermal storage steam device 100 further includes: a heat preservation water tank 7 and a water pump 8. The heat preservation water tank 7 stores a sufficient amount of water for the steam generator 42 to vaporize and use.

[0066] The insulated water tank 7 has a water outlet 71, and a heat exchange water flow channel 62 is formed in the heat exchanger 6, and the water outlet 71 is connected to the heat exchange water flow channel 62. The water pump 8 is used to drive the water in the insulated water tank 7 to be supplied to the heat exchanger 6. Under the action of the water pump 8, the water in the insulated water tank 7 is automatically supplied to the heat exchange water flow channel 62, so that the water in the heat exchange water flow channel 62 is kept sufficient and flows to the steam generator 42 at an appropriate speed. In addition, the arrangement of the water pump 8 is conducive to the steam generator 42 and the heat exchanger 6 forming a staggered arrangement in the longitudinal direction. The steam generator 42 is arranged at the upper part of the heat exchanger 6, and the water pump 8 is conducive to pressurizing the water in the heat exchange water flow channel 62 and pumping it into the steam generator 42. The overall arrangement of the electric thermal storage steam device 100 is made more compact, saving the arrangement space.

[0067] Optionally, a water pump 8 is provided on the water outlet pipeline connected to the water outlet 71 , and the water pump 8 is also connected to the heat exchanger 6 .

[0068] In some examples, the water pump 8 is connected to a control system. When the water level detected by the aforementioned first liquid level gauge is lower than a preset value, the control system controls the water pump 8 to turn on, and the water pump 8 pumps the water in the insulated water tank 7 into the heat exchanger 6 and the steam generator 42.

[0069] Optional, such as Figure 1 As shown, the insulated water tank 7 is also provided with a water inlet 75 , and the setting position of the water inlet 75 is higher than the setting position of the water outlet 71 to reduce the water pressure when replenishing water to the insulated water tank 7 .

[0070] Optionally, a second liquid level gauge (not shown) is provided in the insulated water tank 7 at a position not lower than the water outlet 71. The second liquid level gauge is used to detect the water level in the insulated water tank 7. The second liquid level gauge is connected to the control system. When the water level is lower than a preset water level, water is added to the insulated water tank 7.

[0071] Optional, such as Figure 1 As shown, the insulated water tank 7 is also provided with a drain port 74, and a drain valve or a plug is provided on the drain port 74 to control the drainage of the insulated water tank 7. That is, when the insulated water tank 7 needs to be cleaned, after cleaning the inner wall of the insulated water tank 7, the sewage and dirt are discharged from the drain port 74.

[0072] In some embodiments, Figure 1 As shown, a condensate return pipe 76 is connected between the steam generator 42 and the insulated water tank 7, and a steam trap 73 is provided on the condensate return pipe 76. The steam trap 73, as a steam trap, can automatically identify steam and water, and continuously discharge the condensate in the steam-heated pipeline to the outside of the pipeline. In the present invention, it can be continuously discharged into the insulated water tank 7, thereby achieving the purpose of automatic steam blocking and water drainage, saving water resources, and reducing the condensate content in the steam pipeline.

[0073] Optional, such as Figure 1As shown, the thermal insulation water tank 7 is also provided with a condensed water return port 72 , and the condensed water return port 72 is connected to the condensed water return pipe 76 .

[0074] In some examples, the heat exchanger 6 includes a heat exchange shell, and the heat exchange air duct 61 and the heat exchange water flow channel 62 in the heat exchange shell are arranged in a nested manner. The heat exchange water flow channel 62 is formed as a curved pipe, and the outside of the heat exchange water flow channel 62 is formed as the heat exchange air duct 61.

[0075] Of course, in other examples, the heat exchange air duct 61 is formed as a curved pipe, and the space between the heat exchange air duct 61 and the heat exchange shell is formed as a water exchange hot flow channel 61. This facilitates the flow of air from the high-temperature air duct 12 to the heat exchange air duct 61, and also facilitates the flow of water in the water exchange hot flow channel 62. This is beneficial to the heat exchange between water and hot air.

[0076] Optionally, the heat exchange air duct 61 is two parallel pipes, the two heat exchange air ducts 61 are respectively connected to the two heat exchangers 6, each heat exchanger 6 is formed with a hot water flow channel 62, the water inlet end of each hot water flow channel 62 is respectively connected to a water pump 8, and the water outlet ends of the two hot water flow channels 62 are combined and lead to the steam generator 42. This is conducive to improving the speed at which the heat exchanger 6 supplies boiling water to the steam generator 42.

[0077] In some embodiments of the present invention, Figure 1 As shown, the water inlet end of the insulated water tank 7 is connected to a water softener 9. The water softener 9 can soften the tap water to prevent the water entering the steam generator 42 from scaling during the vaporization process, thereby reducing the vaporization efficiency of the water after absorbing heat.

[0078] Optionally, the water softener 9 includes a softening water device 91 and an automatic molten salt device 92, one end of the softening water device 91 is connected to a tap water inlet pipe, and the other end of the softening water device 91 is connected to a tap water outlet pipe, and the softening water device 91 adsorbs calcium, magnesium, sodium and other ions in the water and retains them in the softening water device 91. The softening water device 91 can use existing ion exchange resin adsorbers and other equipment, which will not be described in detail here. A replacement solution can be added to the automatic molten salt device 92 to rinse and regenerate the ion exchange resin in the softening water device 91 at intervals.

[0079] Optionally, an inlet valve 911 is provided on the tap water inlet pipe, and an outlet valve 912 is provided on the tap water outlet pipe. Both the inlet valve 911 and the outlet valve 912 are connected to a control system. When the water level of the aforementioned second liquid level gauge is lower than a preset value, the control system controls the outlet valve 912 and the inlet valve 911 to open at the same time, and the softening water equipment 91 starts working and transports the softened tap water to the insulated water tank 7.

[0080] In some embodiments of the present invention, Figure 1As shown, an insulating layer plate 32 is provided around the electric heat storage body 31, a heat preservation cavity is formed between the insulating layer plate 32 and the shell 1, and a heat storage cavity 11 is formed inside the insulating layer plate 32. The insulating layer plate 32 provided around the electric heat storage body 31 can effectively prevent the heat in the heat storage cavity 11 from diffusing to the surroundings, so as to ensure that the heat source has sufficient heat.

[0081] Optionally, air inlets and air outlets are provided on opposite sides of the insulating and heat-insulating layer plate 32 around the electric heat storage body 31 (not shown). This can isolate the low-temperature air duct 13 and the high-temperature air duct 12, so that the wind in the low-temperature air duct 13 enters the heat storage chamber 11 from the air inlet, exchanges heat with the electric heat storage body 31, and then enters the high-temperature air duct 12 from the air outlet, so that the air inlet and outlet are more concentrated.

[0082] Optionally, the upper part of one side of the housing 1 is the outlet end of the high-temperature air duct 12, and the lower part of the same side of the housing 1 is the inlet end of the low-temperature air duct 13. An insulating heat preservation layer 32 is provided between the upper high-temperature air duct 12 and the lower low-temperature air duct 13 to form a partition, thereby preventing air of different temperatures from mixing at the beginning and the end, resulting in heat exchange and wasted heat.

[0083] Optionally, the air outlet of the high-temperature air duct 12 is connected to the heat-conducting air duct 41 and the heat-exchanging air duct 61 , the air inlet of the low-temperature air duct 13 is connected to the circulating fan 2 , and the air inlet of the circulating fan 2 is connected to the heat exchanger 6 and the steam generating device 4 in sequence.

[0084] Optionally, the insulation layer board 32 includes a mica board. The mica board has both excellent high temperature resistance and insulation properties.

[0085] In some embodiments, Figure 1 As shown, a plurality of layers of insulation bricks 33 are provided in the insulation cavity, and the insulation bricks 33 support the electric heat storage body 31. The insulation bricks 33 can support the upper electric heat storage body 31 on the one hand, and can form a low-temperature air duct 13 with a stable shape on the other hand.

[0086] Optionally, the insulation bricks 33 include ceramic bricks and glass bricks.

[0087] In some examples of the present invention, Figure 3 and Figure 4 As shown, the electric heat storage body 31 includes a heating element 34 and a multi-layer heat storage brick 311. The heating element 34 is connected to the high-voltage power transmission equipment and electrically heats the heat storage brick 311 to 800-850°C. The electric heat storage body 31 exchanges heat with the wind in the heat storage chamber 11 to form hot air at 400-600°C and transports it to the high-temperature air duct 12. The multi-layer heat storage brick 311 is superimposed on each other, which increases the structural strength of the brick body and can adjust the deformation of the brick body caused by the volume expansion of the heat storage brick 311 itself.

[0088] Optionally, the heat storage bricks 311 include magnesium oxide bricks and iron oxide bricks.

[0089] Optionally, the heat storage brick 311 is a brick body composed of 92% magnesium oxide with a rated heat storage temperature of 800°C.

[0090] Optionally, the electric heat storage body 31 is a cube formed by stacking heat storage bricks 311 , and the heating element 34 runs through the heat storage bricks 311 .

[0091] Favorable, such as Figure 4 As shown, a first groove 311A ​​is formed on one side of the heat storage brick 311, and the first grooves 311A ​​of two adjacent heat storage bricks 311 are butted to accommodate the heating element 34. When two first grooves 311A ​​are butted, a complete groove body is formed, and when a plurality of butted first grooves 311A ​​are butted from the air inlet direction to the air outlet direction, a complete heat exchange air duct is formed, which is conducive to strengthening the interconnection of the holes and enhancing heat transfer.

[0092] Optionally, the density of the heating element 34 near the air outlet of the heat storage chamber 11 is smaller than that of the heating element 34 near the air inlet of the heat storage chamber 11. It can be understood that, since the air inlet of the heat storage chamber 11 is connected to the low-temperature air duct 13, and the air outlet of the heat storage chamber 11 is connected to the high-temperature air duct 12, the temperature near the electric heat storage body 31 near the air inlet is relatively low, and the electric heat storage body 31 consumes a lot of energy when exchanging heat with the wind near the air inlet; while the temperature near the electric heat storage body 31 near the air outlet is relatively high, and the electric heat storage body 31 consumes less energy when exchanging heat with the wind near the air outlet. When the arrangement density of the heating element 34 near the air inlet of the electric heat storage body 31 is increased (i.e., arranged more densely), and the arrangement density of the heating element 34 near the air outlet of the heat storage body 31 is reduced (i.e., arranged more sparsely), it is beneficial to improve the overall heat exchange efficiency of the electric heat storage body 31, and make the temperature of each part of the wind around the electric heat storage body 31 more uniform.

[0093] Optional, such as Figure 3 As shown, the structure of the heating element 34 varies in sections. Figure 3 Taking the partition formed by the vertical lines shown in the figure as an example, the heating elements 34 are sparsely arranged at the end close to the air outlet, while the heating elements are densely arranged at the end close to the air inlet, and the density of the heating elements 34 located in the middle area is between the density of the heating elements 34 at both ends.

[0094] Therefore, the differentiated arrangement of the heating element 34 according to the circulating air temperature can effectively improve the utilization rate of the heating element 34 and ensure stable heat exchange between the electric heat storage body 31 and the wind flowing through the heat storage chamber 11.

[0095] Optional, such as Figure 3As shown, the heating element 34 includes heating wires, which are wavy in shape. The wavy heating wires near the air outlet have a larger wave pitch and are loosely arranged, while the wavy heating wires near the air inlet have a smaller pitch and are densely arranged.

[0096] Optionally, the heating element 34 includes a plurality of heating tubes with different powers, the heating element 34 near the air inlet has a larger power, and the heating element 34 near the air outlet has a smaller power. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0097] Optionally, the heating element 34 includes a plurality of heating tubes of different lengths, the input ends of the heating tubes passing through the electric heat storage body 31 near the air inlet, and the output ends of the heating tubes having different lengths from the air outlet.

[0098] Favorable, such as Figure 4 As shown, a second groove 311B is formed on one side of the heat storage brick 311, and two adjacent second grooves 311B are butted to accommodate the temperature sensor 35. This prevents the temperature sensor 35 from being squeezed, and also facilitates monitoring the temperature inside the electric heat storage body 31.

[0099] Optionally, a plurality of far-infrared temperature sensors are provided at intervals on one side of the electric heat storage body 31 along the air inlet direction toward the air outlet direction, so as to monitor the temperature changes of various parts of the electric heat storage body 31 in real time.

[0100] In addition, a high-temperature air duct temperature sensor is connected to the outlet of the high-temperature air duct 12 to monitor the hot air temperature of the high-temperature air duct in real time.

[0101] In the example of the present invention, Figure 1 As shown, the voltage output by the high-voltage power transmission equipment 10 is 10kV. The heating element 34 in the electric heat storage body 31 is connected to the input voltage of 10kV. Specifically, the 10kV high-voltage cable enters the 10kV high-voltage distribution room through the wall bushing, and the 10kV high-voltage power supply is connected to the heat storage body electric heating wire group through the incoming line metering switch cabinet, the feeder cabinet and the contactor cabinet.

[0102] Optionally, the high-voltage power transmission equipment 10 further includes a contactor and a protective box.

[0103] To better understand the solution of the embodiment of the present invention, the structure of an electric thermal storage steam device 100 in a specific embodiment of the present invention is described below with reference to the accompanying drawings.

[0104] like Figure 1 As shown, an electric heat storage steam device 100 includes a shell 1, a circulating fan 2, an electric heat storage body 31, a steam generating device 4, a heat exchanger 6, a heat preservation water tank 7, a water pump 8 and a water softener 9.

[0105] Among them, Figure 1As shown, a heat storage chamber 11, a high-temperature air duct 12 and a low-temperature air duct 13 are defined in the housing 1. The heat storage chamber 11 has an air outlet and an air inlet (not shown), the air outlet is connected to the high-temperature air duct 12, and the air inlet is connected to the low-temperature air duct 13. The electric heat storage body 31 is arranged in the heat storage chamber 11. After the electric heat storage body 31 is energized, it generates heat and exchanges heat with the air flow passing through to form hot air leading to the high-temperature air duct 12.

[0106] like Figure 3 and Figure 4 As shown in the figure, the electric heat storage body 31 is provided with a three-dimensional shape formed by stacking multiple layers of heat storage bricks 311. Each heat storage brick 311 has a first groove 311A ​​on one side and a second groove 311B on the other side. The two first grooves 311A ​​of adjacent heat storage bricks 311 are connected to form a larger groove body and accommodate the heating element 34; the two second grooves 311B of adjacent heat storage bricks 311 are connected to form a smaller groove body and accommodate the temperature sensor 35. When the heating element 34 is arranged, the heating element 34 in the electric heat storage body 31 near the air inlet is arranged more densely, and the heating element 34 in the electric heat storage body 31 near the air outlet is arranged more sparsely. A plurality of far-infrared temperature sensors are arranged at intervals on the surface of the electric heat storage body 31 extending from the air inlet to the air outlet. The heating element 34 in the electric heat storage body 31 is connected to the 10kV high voltage electricity input by the external high-voltage power transmission equipment 10. After the heating element 34 generates heat, the electric heat storage body 31 forms a heat source with a heating temperature of up to 850°C, and the temperature of the heated hot air is about 500°C. The hot air flows from the air outlet to the high-temperature air duct 12. The high-temperature air duct 12 flows to the outside of the shell 1 and is connected to the external steam generating device 4 or the heat exchanger 6. The low-temperature air duct 13 is connected to the circulating fan 2. The low-temperature air duct 13 is provided with a heat preservation brick 33 to support the upper electric heat storage body 31.

[0107] like Figure 1 and Figure 2As shown, the steam generating device 4 includes a heat-conducting air duct 41, a steam generator 42, and a heat exchange tube bundle 43. The heat-conducting air duct 41 is connected between the high-temperature air duct 12 and the low-temperature air duct 13 to form a first circulation air duct with the shell 1. The heat-conducting air duct 41 is connected with the heat-conducting tube bundle 43, and the middle part of the heat-conducting tube bundle 43 penetrates into the steam generator 42. The heat-conducting tube bundle 43 includes a plurality of heat-conducting tubes 431 arranged in parallel, one end of the heat-conducting tube 431 is formed as a low-temperature end 433, and the other end of the heat-conducting tube 431 is formed as a high-temperature end 432. The high-temperature ends 432 of the plurality of heat-conducting tubes 431 are connected to the air distribution tube 434 and then connected to the high-temperature section 411 of the heat-conducting air duct 41, and the low-temperature ends 433 of the plurality of heat-conducting tubes 431 are connected to another air distribution tube 434 and then connected to the low-temperature section 412 of the heat-conducting air duct 41. The first circulation air duct is provided with a switch valve, an induced draft fan 413 and a mixing fan 414, and the steam generator 42 is provided with a pressure transmitter 423. When the pressure transmitter 423 detects that the air pressure in the steam generator 42 is lower than the preset value, the switch valve, the induced draft fan 413 and the mixing fan 414 are controlled to open, and the hot air blown out from the high-temperature air duct 12 is sent into the first circulation air duct and exchanges heat with the water in the evaporator 42 through the heat exchange tube bundle 43, so as to perform thermal compensation on the water temperature in the evaporator 42. The low-temperature air formed after heat exchange returns to the shell 1 from the low-temperature air duct 13. A condensate return pipe 76 is provided between the steam generator 42 and the insulated water tank 7, and a steam trap 73 is provided on the condensate return pipe 76.

[0108] like Figure 1 As shown, the water inlet end of the heat exchange water flow channel 62 is connected to the water pump 8, and the water pump 8 is connected to the heat preservation water tank 7. When the liquid level of the first liquid level gauge is lower than the preset value, the water pump 8 is controlled to start and add water to the heat exchanger 6. The heat preservation water tank 7 includes a water outlet 71, a condensate return port 72, a drain port 74 and a water inlet 75. The water outlet 71 is connected to the water pump 8, the water inlet 75 is connected to the water softener 9, the drain port 74 is used to discharge the dirt at the bottom, the condensate return port 72 is connected to the condensate return pipe 76, and a steam trap 73 is arranged on the condensate return pipe 76 to allow the generated condensate to flow back to the heat preservation water tank 7. The elevation of the water outlet 71 is higher than that of the drain outlet 74 , and the elevation of the water inlet 75 is higher than that of the water outlet 71 . A second liquid level gauge is provided on the inner wall of the insulated water tank 7 near the water outlet 71 . When the liquid level here is lower than a preset value, the water in the water softener 9 is controlled to add water to the insulated water tank 7 .

[0109] When the electric heat storage body 31 has sufficient heat storage, the hot air in the high-temperature air duct 12 usually only flows to the second circulation air duct, which includes the heat exchange air duct 61, the high-temperature air duct 12, and the low-temperature air duct 13 in the heat exchanger 6. The heat exchanger 6 also includes a heat exchange shell and a hot water flow channel 62. The hot water flow channel 62 is arranged in a serpentine shape in the heat exchange shell, and the heat exchange shell outside the hot water flow channel 62 constitutes the heat exchange air duct 61. The water inlet end of the hot water flow channel 62 is connected to the water stored in the thermal insulation water tank 7, and the water outlet end of the hot water flow channel 62 is connected to the water inlet 421 of the steam generator 42. Under the action of the circulating fan 2, the hot air passing through the high-temperature air duct 12 flows into the heat exchange air duct 61 and heats the water in the hot water flow channel 62 to a boiling temperature. The low-temperature air in the heat exchange air duct 61 after heat exchange returns to the shell 1 from the low-temperature air duct 13.

[0110] When the electric heat storage body 31 does not store enough heat, the hot air in the high-temperature air duct 12 not only flows to the second circulation air duct, but also flows to the first circulation air duct, and the water in the steam generator 42 is heated through the first circulation air duct to ensure that sufficient steam is generated in the steam generator 42 and transported to the user end.

[0111] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0112] Other components of the electric thermal storage steam device 100 according to the embodiment of the present invention, such as the thermal storage principle of the electric thermal storage body 31 , are known to those skilled in the art and will not be described in detail here.

[0113] In the description of this specification, the description with reference to the terms "embodiment", "example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0114] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An electric thermal storage steam device, characterized in that: include: A shell, wherein a heat storage chamber, a high-temperature air duct and a low-temperature air duct are defined in the shell, the heat storage chamber has an air outlet and an air inlet, the air outlet is connected to the high-temperature air duct, and the air inlet is connected to the low-temperature air duct; A circulation fan, the circulation fan is used to drive the airflow in the low-temperature air duct to flow to the heat storage chamber, and drive the airflow in the heat storage chamber to flow to the high-temperature air duct; An electric heat storage body, the electric heat storage body is arranged in the heat storage chamber, the electric heat storage body generates heat after being energized and exchanges heat with the airflow passing through to form hot air leading to the high-temperature air duct; A steam generating device, the steam generating device comprising a heat-conducting air duct, a steam generator and a heat-exchange tube bundle, the heat-conducting air duct being connected between the high-temperature air duct and the low-temperature air duct to form a first circulation air duct with the shell, and at least a portion of the heat-exchange tube bundle being arranged in the steam generator to supplement the temperature of water in the steam generator; A heat exchanger, the heat exchanger comprising a heat exchange air duct, the heat exchange air duct being arranged between the high-temperature air duct and the low-temperature air duct to form a second circulation air duct with the shell, the heat exchanger heating the water flowing through the heat exchanger and inputting the water into the steam generator to generate steam; The steam generator has a water inlet, a hot water flow channel is formed in the heat exchanger, and the water inlet of the steam generator is in communication with the hot water flow channel.

2. The electric thermal storage steam device according to claim 1, characterized in that: The steam generator has a high-temperature steam outlet, the heat exchange tube bundle includes a plurality of heat exchange tubes, the heat exchange tube bundle penetrates into the steam generator, two ends of the heat exchange tube bundle extend from the steam generator respectively to form a high-temperature end and a low-temperature end, the heat-conducting air duct includes a high-temperature section and a low-temperature section, the high-temperature end is connected to the high-temperature section, the low-temperature end is connected to the low-temperature section, and the low-temperature section is connected to the low-temperature air duct.

3. The electric thermal storage steam device according to claim 1, characterized in that: The first circulating air duct is provided with a switch valve for opening and closing the first circulating air duct, and the first circulating air duct is also provided with an induced draft fan.

4. The electric thermal storage steam device according to claim 3, characterized in that: A pressure transmitter is provided in the steam generator, and the pressure transmitter monitors the steam pressure in the steam generator and controls the opening and closing of the switch valve and the induced draft fan.

5. The electric thermal storage steam device according to claim 1, characterized in that: Also includes: A heat-insulating water tank, wherein the heat-insulating water tank has a water outlet, and the water outlet is connected to the heat-exchanging water flow channel; A water pump is used to drive the water in the thermal insulation water tank to be supplied toward the heat exchanger.

6. The electric thermal storage steam device according to claim 5, characterized in that: A condensate return pipe is connected between the steam generator and the insulated water tank, and a steam trap is arranged on the condensate return pipe; and a water inlet end of the insulated water tank is connected to a water softener.

7. The electric thermal storage steam device according to any one of claims 1 to 6, characterized in that: An insulating layer plate is arranged around the electric heat storage body, a heat preservation cavity is formed between the insulating layer plate and the shell, the heat storage cavity is formed inside the insulating layer plate, and multiple layers of heat preservation bricks are arranged in the heat preservation cavity, and the heat preservation bricks support the electric heat storage body.

8. The electric thermal storage steam device according to any one of claims 1 to 6, characterized in that: The electric heat storage body includes a heating element and multi-layer heat storage bricks. The heating element is connected to a high-voltage power transmission device and electrically heats the heat storage bricks to 800-850° C. The electric heat storage body exchanges heat with the wind in the heat storage chamber to form hot wind at 400-600° C. and transports it to the high-temperature air duct.

9. The electric thermal storage steam device according to claim 8, characterized in that: A first groove is formed on one side of the heat storage brick, and the first grooves of two adjacent heat storage bricks are butted together to accommodate the heating element; a second groove is formed on one side of the heat storage brick, and two adjacent second grooves are butted together to accommodate the temperature sensor.

10. The electric thermal storage steam device according to claim 8, characterized in that: The density of the heating element close to the air outlet of the heat storage chamber is smaller than that of the heating element close to the air inlet of the heat storage chamber.

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